This invention relates to air texturing of yarn and, more particularly, to improvements in a fluid jet apparatus used to texture the yarn.
Fluid jet apparatus for texturing yarn usually comprises a conically-tipped yarn guiding tube or needle for introducing yarn into the apparatus, a port for supplying pressurized fluid to a space surrounding the forward end of the needle and a venturi-shaped nozzle through which yarn and fluid leave the jet. Yarn is usually introduced into such a jet by moving the forward end of the yarn needle close to the converging entrance of the nozzle so that the flow of pressurized fluid is severely throttled between the two, producing an air pressure less than atmospheric at the forward end of the needle. This induces an inward flow of atmospheric air through the needle which will draw an end of yarn into and through the jet. This aspirating (stringup) position, however, generally does not permit sufficient fluid to pass through the jet to give optimum yarn texturing action. Therefore, the gap between the forward end of the yarn needle and the nozzle entrance is usually increased, i.e, the needle is moved back to some preset operating position, to provide optimum yarn texturing action.
Jets have been made in the past which are adjustable between fixed positions for stringup and operating conditions but these include mechanical assists such as springs to effect adjustments and as a consequence the manufacturing costs of such jets are high.